Switched reluctance motor is a motor, structure of which is very simple while the speed of rotation is easy to control up to hundreds of thousands of rpm owing to advances in the electronic switching technologies. Despite such advantages, its industrial applications are very limited presently mainly because its motion generation mechanism inherently involves high level of electromagnetic excitation forces in the radial direction and, consequently, high sound pressure level.
The shape of the electromagnetic excitation force in the radial direction, which is the major source of the vibration and noise, is dependent on characteristics of the switching circuit as well as switching angles. In this paper, effects of the latter, i.e., switching angles, on the noise and vibration generations are investigated since this is far simpler than dealing with improvements of switching circuit or motor structure. Key parameters of the switching angles are timing of switch-on and switch-off at a chosen stator tooth when a rotor tooth passes through it. Vibrations are measured by changing the switching angles and their relations to the modal properties of the motor structure are studied. Based on the observations, theoretical models for the force generation are derived and suggestions are proposed to reduce the noise and vibrations.
